Calculations of Basic and Diluted Net Income Per Common Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Oct. 31, 2012	Jul. 31, 2012	Apr. 30, 2012	Jan. 31, 2012	Oct. 31, 2011	Jul. 31, 2011	Apr. 30, 2011	Jan. 31, 2011	Oct. 31, 2012	Oct. 31, 2011	Oct. 31, 2010
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Income from continuing operations	$ 27,705	$ 12,626	$ 11,747	$ 10,640	$ 18,182	$ 27,911	$ 14,200	$ 8,405	$ 62,718	$ 68,698	$ 63,870
(Loss) income from discontinued operations, net of taxes	(42)	(49)	(35)	(10)	(134)	(36)	(8)	(15)	(136)	(194)	251
Net income	$ 27,663	$ 12,577	$ 11,712	$ 10,630	$ 18,048	$ 27,875	$ 14,192	$ 8,390	$ 62,582	$ 68,504	$ 64,121
Weighted-average common and common equivalent shares outstanding-Basic									53,987	53,121	52,117
Effect of dilutive securities:
Weighted-average common and common equivalent shares outstanding-Diluted									54,914	54,103	52,908
Net income per common share
Basic	$ 0.50	$ 0.23	$ 0.22	$ 0.20	$ 0.34	$ 0.52	$ 0.27	$ 0.16	$ 1.16	$ 1.29	$ 1.23
Diluted	$ 0.50	$ 0.23	$ 0.21	$ 0.20	$ 0.33	$ 0.51	$ 0.26	$ 0.16	$ 1.14	$ 1.27	$ 1.21
Stock options
Effect of dilutive securities:
Effect of dilutive securities									277	468	446
Restricted stock units
Effect of dilutive securities:
Effect of dilutive securities									369	293	261
Performance shares
Effect of dilutive securities:
Effect of dilutive securities									281	221	84